Hurricane Katrina

===Environmental effects===
{{See also|Murphy Oil USA refinery spill}}
{| class="wikitable" style="font-size:92%; float:right; margin-top:0; margin-left:10px; margin-right:0;"
|-
! colspan=3 style="background:#ccf;" | '''Large oil spills caused by Hurricane Katrina'''<br /><small>Spills exceeding {{convert|10000|USgal|L|lk=on}}</small><ref name="msnbcspills"/>
|-
! rowspan = 2 | Spill Location
! colspan = 2 | Quantity
|-
! <small>(US gal)</small> !! <small>(L)</small>
|-
| Bass Enterprises (Cox Bay) || style="text-align:right;"| 3,780,000 || style="text-align:right;"| {{convert|3780000|USgal|L|disp=output number only}}
|-
| Shell ([[Pilottown, Louisiana|Pilot Town]])|| style="text-align:right;"| 1,050,000 || style="text-align:right;"| {{convert|1050000|USgal|L|disp=output number only}}
|-
| Chevron ([[Empire, Louisiana|Empire]])|| style="text-align:right;"| 991,000 || style="text-align:right;"| {{convert|991000|USgal|L|disp=output number only}}
|-
| Murphy Oil ([[Meraux, Louisiana|Meraux]] and [[Chalmette, Louisiana|Chalmette]])|| style="text-align:right;"| 819,000 || style="text-align:right;"| {{convert|819000|USgal|L|disp=output number only}}
|-
| Bass Enterprises ([[Pointe à la Hache, Louisiana|Pointe à la Hache]])|| style="text-align:right;"| 461,000 || style="text-align:right;"| {{convert|461000|USgal|L|disp=output number only}}
|-
| Chevron ([[Port Fourchon, Louisiana|Port Fourchon]])|| style="text-align:right;"| 53,000 || style="text-align:right;"| {{convert|53000|USgal|L|disp=output number only}}
|-
| Venice Energy Services ([[Venice, Louisiana|Venice]])|| style="text-align:right;"| 25,000 || style="text-align:right;"|{{convert|25000|USgal|L|disp=output number only}}
|-
| Shell Pipeline Oil (Nairn)|| style="text-align:right;"| 13,440 || style="text-align:right;"| {{convert|13440|USgal|L|disp=output number only}}
|-
| Sundown Energy (West Potash)|| style="text-align:right;"| 13,000 || style="text-align:right;"| {{convert|13000|USgal|L|disp=output number only}}
|}
Katrina also had a profound impact on the environment. The storm surge caused substantial [[Coastal erosion|beach erosion]], in some cases completely devastating coastal areas. In Dauphin Island (a [[barrier island]]), approximately {{convert|90|mi|km|abbr=on}} to the east of the point where the hurricane made landfall, the sand that comprised the island was transported across the island into the [[Mississippi Sound]], pushing the island towards land.<ref>{{cite web | author = United States Geological Survey | date = September 14, 2005 | url = http://coastal.er.usgs.gov/hurricanes/katrina/lidar/dauphin-island.html | title = Daupin Island – Pre- and Post-Storm 3D Topography | website = Hurricane Katrina Impact Studies | publisher = [[USGS]] | access-date = June 5, 2006 | author-link = United States Geological Survey | archive-url = https://web.archive.org/web/20150312144109/http://coastal.er.usgs.gov/hurricanes/katrina/lidar/dauphin-island.html | archive-date = March 12, 2015 | url-status = live}}</ref> The storm surge and waves from Katrina also severely damaged the [[Chandeleur Islands]], which had been affected by Hurricane Ivan the previous year.<ref>{{cite web |author=United States Geological Survey |date=September 14, 2005 |url=http://coastal.er.usgs.gov/hurricanes/katrina/photo-comparisons/chandeleur.html |title=Before and After Photo Comparisons: Chandeleur Islands |website=Hurricane Katrina Impact Studies |publisher=USGS |access-date=June 5, 2006 |archive-url=https://web.archive.org/web/20060614070836/http://coastal.er.usgs.gov/hurricanes/katrina/photo-comparisons/chandeleur.html |archive-date=June 14, 2006 |url-status=live}}</ref> The US Geological Survey has estimated {{convert|217|sqmi|km2|abbr=on}} of land was transformed to water by the hurricanes Katrina and Rita.<ref>[http://www.nwrc.usgs.gov/releases/pr06_002.htm "USGS Reports Latest Land Change Estimates for Louisiana Coast", USGS National Wetlands Research Center, Oct 3, 2006] {{Webarchive|url=https://web.archive.org/web/20080513083524/http://www.nwrc.usgs.gov/releases/pr06_002.htm |date=May 13, 2008}}, accessed May 7, 2008.</ref> Before the storm, [[subsidence]] and [[erosion]] caused loss of land in the Louisiana wetlands and [[bayou]]s. This, along with the canals built in the area, let Katrina keep more of its intensity when it struck.<ref>{{cite book|page=[https://archive.org/details/ravagingtide00mike/page/22 22]|first=Mike|last=Tidwell|title=The Ravaging Tide: Strange Weather, Future Katrinas, and the Coming Death of America's Coastal Cities|publisher=Free Press|year=2006|isbn=978-0-7432-9470-6|access-date=April 14, 2010|url=https://archive.org/details/ravagingtide00mike|url-access=registration|quote=The Ravaging Tide: Strange Weather, Future Katrinas, and the Coming Death of America's Coastal Cities book.}}</ref> The lands that were lost were breeding grounds for marine mammals, brown [[pelican]]s, [[turtle]]s, and [[fish]], and migratory species such as [[redhead duck]]s.<ref name="CRS environment"/> Overall, about 20% of the local [[marsh]]es were permanently overrun by water as a result of the storm.<ref name="CRS environment"/>

The damage from Katrina forced the closure of 16 [[National Wildlife Refuge]]s. Breton National Wildlife Refuge lost half its area in the storm.<ref name="FWS impact">{{cite web | author = United States Fish and Wildlife Service | date = September 9, 2005 | url = http://www.fws.gov/southeast/news/2005/r05-088.html | title = U.S. Fish and Wildlife Service Conducting Initial Damage Assessments to Wildlife and National Wildlife Refuges | publisher = [[U.S. Fish and Wildlife Service|USFWS]] | access-date = June 5, 2006 | author-link = United States Fish and Wildlife Service | archive-url = https://web.archive.org/web/20051029213935/http://www.fws.gov/southeast/news/2005/r05-088.html | archive-date = October 29, 2005 | url-status = live}}</ref> As a result, the hurricane affected the habitats of [[sea turtle]]s, Mississippi [[sandhill crane]]s, [[red-cockaded woodpecker]]s, and [[Alabama Beach Mouse|Alabama Beach mice]].<ref name="FWS impact"/>

Katrina produced massive tree loss along the Gulf Coast, particularly in Louisiana's [[Pearl River Basin]] and among [[bottomland hardwood forest]]s. Before the storm, the standard mortality rate for the area's trees was 1.9%, but this interval increased to 20.5% by the end of 2006.<ref>{{Cite journal|last=Chapman|first=Elise|year=2008|title=Hurricane Katrina Impacts on Forest Trees of Louisiana's Pearl River Basin|journal=Forest Ecology and Management|volume=256|issue=5|pages=883–889|doi=10.1016/j.foreco.2008.05.057}}</ref> Delayed mortality as an effect of the storm continued with rates up to 5% until 2011.<ref>{{Cite journal|last=Henkel|first=Theryn|year=2016|title=Delayed Tree Mortality and Chinese Tallow Explosion in Louisiana Bottomland Hardwood Forest Following Hurricane Katrina|url=http://www.escholarship.org/uc/item/6kh4k7vb|journal=Forest Ecology and Management|volume=378|pages=222–232|doi=10.1016/j.foreco.2016.07.036|doi-access=free}}</ref> This significant loss in [[biomass]] caused greater decay and an increase in carbon emissions. For example, by 2006 the decreased biomass in bottomland hardwood forests contributed an amount of carbon which equated to roughly 140% of the net annual U.S. [[carbon sink]] in forest trees.<ref>{{cite journal|title=Hurricane Katrina's Carbon Footprint on U.S. Gulf Coast Forests|first1=Jeffrey Q.|last1=Chambers|first2=Jeremy I.|last2=Fisher|first3=Hongcheng|last3=Zeng|first4=Elise L.|last4=Chapman|first5=David B.|last5=Baker|first6=George C.|last6=Hurtt|date=January 1, 2007|journal=Science|volume=318|issue=5853|pages=1107|doi=10.1126/science.1148913|pmid=18006740|jstor=20051600|bibcode=2007Sci...318.1107C|s2cid=477946}}</ref>
[[File:Chandeleur L5 Oct2004Sep2005.jpg|thumb|left|The [[Chandeleur Islands]], before Katrina (left) and after (right), showing the impact of the storm along coastal areas.]]
The storm caused [[oil spill]]s from 44 facilities throughout southeastern Louisiana, which resulted in over {{convert|7|e6USgal|m3}} of [[oil]] being leaked. Some spills were only a few hundred gallons and most were contained on-site, though some oil entered the ecosystem and residential areas. After a spill at the [[Murphy Oil]] refinery, for example, 1,800&nbsp;homes were oiled in the towns of [[Chalmette, Louisiana|Chalmette]] and [[Meraux, Louisiana|Meraux]].<ref name="msnbcspills">{{cite news | first=Miguel | last=Llanos | title=44 oil spills found in southeast Louisiana | work=NBC News | url=https://www.nbcnews.com/id/9365607 | publisher=NBC News | date=September 19, 2005 | access-date=June 15, 2006 | archive-url=https://web.archive.org/web/20131104013837/http://www.nbcnews.com/id/9365607/ | archive-date=November 4, 2013 | url-status=live}}</ref> Unlike [[Hurricane Ivan]], no offshore oil spills were officially reported after Hurricane Katrina. However, Skytruth reported some signs of surface oil in the Gulf of Mexico.<ref name="msnbcspills"/>

Finally, as part of the cleanup effort, the floodwaters that covered New Orleans were pumped into Lake Pontchartrain, a process that took 43 days to complete.<ref name="katreport"/> These residual waters contained a mix of raw [[sewage]], [[bacteria]], [[heavy metals]], [[pesticide]]s, toxic chemicals, and [[oil]], which sparked fears in the scientific community of massive numbers of fish dying.<ref name="CRS environment"/> The toxic floodwaters were also a danger for New Orleans, due to the presence of petrochemical chemicals and industrial toxins close to the city. Thomas La Point, director of the Institute of Applied Sciences at the [[University of North Texas]], stated that "[a] toxic soup would be a good way to describe the situation".<ref>{{Cite web |last=News |first=A. B. C. |title=Katrina Creates a 'Toxic Soup' |url=https://abcnews.go.com/Technology/HurricaneKatrina/story?id=1081623&page=1 |access-date=2024-04-14 |website=ABC News |language=en}}</ref>